The invention generally relates to a method for controlling a means for controlling displacement of a suspended seat, and more particularly the invention relates to a method for controlling a damper in a suspended seat system by calculating the positional power of the system and using the calculated positional power value as a basis for tuning the system operating parameters.
In a semi-active seat suspension system the displacement of the seat is controlled by a damper which may be comprised of a damper that includes a volume of a field responsive material such as magnetorheological (MR) material or a servo valve controlled damper, etc. The field responsive material and servo valve controlled dampers serve to quickly modify the motion control forces supplied by the damper or other motion control means in a seat suspension system. During operation of the system, as required, a signal is sent to the damper to modify the supplied damping. Frequently, when large magnitude non-typical inputs are experienced a gain value is applied to the control signal to rapidly increase the magnitude of the control signal, transmitted to the damper and significantly increase the damping forces.
In prior art seat suspension control systems the gain values applied to system control signals or tunings are fixed for a semi-active seat suspension system. The fixed gain and tuning values are established based on the seat manufacturer, the typical seat occupant weights and inputs that are most frequently experienced when the suspension system is used in the its associated field, for example in busses or trucks. The shortcoming associated with systems that apply fixed gain and tuning values to control signals is that such fixed systems frequently can not sufficiently prevent endstop collisions when either non-typical inputs are imparted on the system or when a seat occupant has a weight that is outside of the tuned weight range.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to providing variable gain values to a control signal. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.
In one aspect of the invention this is accomplished by providing a method for adjusting the gain applied to a control signal to accommodate for large variations in rider weight and/or input severity and thereby provide rider comfort over a wider range of conditions than is possible with fixed gains or tunings. The method of the present invention is adaptable to changes in system operating conditions.
In another aspect of the invention the method of the present invention serves as a displacement regulator that tends to cause the seat displacement to be constant regardless of the weight of the rider or the magnitude of the input displacements.
In yet another aspect of the invention, the method causes the suspension system damper to produce low magnitude control forces during low severity inputs and low rider weights.
Another useful feature of the system is that as the severity of the inputs increases the normal phase lag between the suspended seat input and the output motions found in passively damped seats is reduced. This has the effect of coupling the driver more strongly to the vehicle controls (steering, brake, etc.) making it easier to control the vehicle in question during large vibratory inputs.
The foregoing and other aspects will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawing Figures.